mtd: devices: add support for microchip 48l640 EERAM

The Microchip 48l640 is a 8KByte EERAM connected via SPI.
Signed-off-by: Heiko Schocher <hs@denx.de>
Tested-by: Fabio Estevam <festevam@denx.de>
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20210607033909.1424605-3-hs@denx.de

drivers/mtd/devices/Kconfig

@@ -89,6 +89,12 @@ config MTD_MCHP23K256
 	  platform data, or a device tree description if you want to
 	  specify device partitioning
 
+config MTD_MCHP48L640
+	tristate "Microchip 48L640 EERAM"
+	depends on SPI_MASTER
+	help
+	  This enables access to Microchip 48L640 EERAM chips, using SPI.
+
 config MTD_SPEAR_SMI
 	tristate "SPEAR MTD NOR Support through SMI controller"
 	depends on PLAT_SPEAR || COMPILE_TEST

drivers/mtd/devices/Makefile

@@ -13,6 +13,7 @@ obj-$(CONFIG_MTD_LART)		+= lart.o
 obj-$(CONFIG_MTD_BLOCK2MTD)	+= block2mtd.o
 obj-$(CONFIG_MTD_DATAFLASH)	+= mtd_dataflash.o
 obj-$(CONFIG_MTD_MCHP23K256)	+= mchp23k256.o
+obj-$(CONFIG_MTD_MCHP48L640)	+= mchp48l640.o
 obj-$(CONFIG_MTD_SPEAR_SMI)	+= spear_smi.o
 obj-$(CONFIG_MTD_SST25L)	+= sst25l.o
 obj-$(CONFIG_MTD_BCM47XXSFLASH)	+= bcm47xxsflash.o

drivers/mtd/devices/mchp48l640.c

+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Driver for Microchip 48L640 64 Kb SPI Serial EERAM
+ *
+ * Copyright Heiko Schocher <hs@denx.de>
+ *
+ * datasheet: http://ww1.microchip.com/downloads/en/DeviceDoc/20006055B.pdf
+ *
+ * we set continuous mode but reading/writing more bytes than
+ * pagesize seems to bring chip into state where readden values
+ * are wrong ... no idea why.
+ *
+ */
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/jiffies.h>
+#include <linux/module.h>
+#include <linux/mtd/mtd.h>
+#include <linux/mtd/partitions.h>
+#include <linux/mutex.h>
+#include <linux/sched.h>
+#include <linux/sizes.h>
+#include <linux/spi/flash.h>
+#include <linux/spi/spi.h>
+#include <linux/of_device.h>
+
+struct mchp48_caps {
+	unsigned int size;
+	unsigned int page_size;
+};
+
+struct mchp48l640_flash {
+	struct spi_device	*spi;
+	struct mutex		lock;
+	struct mtd_info		mtd;
+	const struct mchp48_caps	*caps;
+};
+
+#define MCHP48L640_CMD_WREN		0x06
+#define MCHP48L640_CMD_WRDI		0x04
+#define MCHP48L640_CMD_WRITE		0x02
+#define MCHP48L640_CMD_READ		0x03
+#define MCHP48L640_CMD_WRSR		0x01
+#define MCHP48L640_CMD_RDSR		0x05
+
+#define MCHP48L640_STATUS_RDY		0x01
+#define MCHP48L640_STATUS_WEL		0x02
+#define MCHP48L640_STATUS_BP0		0x04
+#define MCHP48L640_STATUS_BP1		0x08
+#define MCHP48L640_STATUS_SWM		0x10
+#define MCHP48L640_STATUS_PRO		0x20
+#define MCHP48L640_STATUS_ASE		0x40
+
+#define MCHP48L640_TIMEOUT		100
+
+#define MAX_CMD_SIZE			0x10
+
+#define to_mchp48l640_flash(x) container_of(x, struct mchp48l640_flash, mtd)
+
+static int mchp48l640_mkcmd(struct mchp48l640_flash *flash, u8 cmd, loff_t addr, char *buf)
+{
+	buf[0] = cmd;
+	buf[1] = addr >> 8;
+	buf[2] = addr;
+
+	return 3;
+}
+
+static int mchp48l640_read_status(struct mchp48l640_flash *flash, int *status)
+{
+	unsigned char cmd[2];
+	int ret;
+
+	cmd[0] = MCHP48L640_CMD_RDSR;
+	cmd[1] = 0x00;
+	mutex_lock(&flash->lock);
+	ret = spi_write_then_read(flash->spi, &cmd[0], 1, &cmd[1], 1);
+	mutex_unlock(&flash->lock);
+	if (!ret)
+		*status = cmd[1];
+	dev_dbg(&flash->spi->dev, "read status ret: %d status: %x", ret, *status);
+
+	return ret;
+}
+
+static int mchp48l640_waitforbit(struct mchp48l640_flash *flash, int bit, bool set)
+{
+	int ret, status;
+	unsigned long deadline;
+
+	deadline = jiffies + msecs_to_jiffies(MCHP48L640_TIMEOUT);
+	do {
+		ret = mchp48l640_read_status(flash, &status);
+		dev_dbg(&flash->spi->dev, "read status ret: %d bit: %x %sset status: %x",
+			ret, bit, (set ? "" : "not"), status);
+		if (ret)
+			return ret;
+
+		if (set) {
+			if ((status & bit) == bit)
+				return 0;
+		} else {
+			if ((status & bit) == 0)
+				return 0;
+		}
+
+		usleep_range(1000, 2000);
+	} while (!time_after_eq(jiffies, deadline));
+
+	dev_err(&flash->spi->dev, "Timeout waiting for bit %x %s set in status register.",
+		bit, (set ? "" : "not"));
+	return -ETIMEDOUT;
+}
+
+static int mchp48l640_write_prepare(struct mchp48l640_flash *flash, bool enable)
+{
+	unsigned char cmd[2];
+	int ret;
+
+	if (enable)
+		cmd[0] = MCHP48L640_CMD_WREN;
+	else
+		cmd[0] = MCHP48L640_CMD_WRDI;
+
+	mutex_lock(&flash->lock);
+	ret = spi_write(flash->spi, cmd, 1);
+	mutex_unlock(&flash->lock);
+
+	if (ret)
+		dev_err(&flash->spi->dev, "write %sable failed ret: %d",
+			(enable ? "en" : "dis"), ret);
+
+	dev_dbg(&flash->spi->dev, "write %sable success ret: %d",
+		(enable ? "en" : "dis"), ret);
+	if (enable)
+		return mchp48l640_waitforbit(flash, MCHP48L640_STATUS_WEL, true);
+
+	return ret;
+}
+
+static int mchp48l640_set_mode(struct mchp48l640_flash *flash)
+{
+	unsigned char cmd[2];
+	int ret;
+
+	ret = mchp48l640_write_prepare(flash, true);
+	if (ret)
+		return ret;
+
+	cmd[0] = MCHP48L640_CMD_WRSR;
+	cmd[1] = MCHP48L640_STATUS_PRO;
+
+	mutex_lock(&flash->lock);
+	ret = spi_write(flash->spi, cmd, 2);
+	mutex_unlock(&flash->lock);
+	if (ret)
+		dev_err(&flash->spi->dev, "Could not set continuous mode ret: %d", ret);
+
+	return mchp48l640_waitforbit(flash, MCHP48L640_STATUS_PRO, true);
+}
+
+static int mchp48l640_wait_rdy(struct mchp48l640_flash *flash)
+{
+	return mchp48l640_waitforbit(flash, MCHP48L640_STATUS_RDY, false);
+};
+
+static int mchp48l640_write_page(struct mtd_info *mtd, loff_t to, size_t len,
+			    size_t *retlen, const unsigned char *buf)
+{
+	struct mchp48l640_flash *flash = to_mchp48l640_flash(mtd);
+	unsigned char *cmd;
+	int ret;
+	int cmdlen;
+
+	cmd = kmalloc((3 + len), GFP_KERNEL | GFP_DMA);
+	if (!cmd)
+		return -ENOMEM;
+
+	ret = mchp48l640_wait_rdy(flash);
+	if (ret)
+		goto fail;
+
+	ret = mchp48l640_write_prepare(flash, true);
+	if (ret)
+		goto fail;
+
+	mutex_lock(&flash->lock);
+	cmdlen = mchp48l640_mkcmd(flash, MCHP48L640_CMD_WRITE, to, cmd);
+	memcpy(&cmd[cmdlen], buf, len);
+	ret = spi_write(flash->spi, cmd, cmdlen + len);
+	mutex_unlock(&flash->lock);
+	if (!ret)
+		*retlen += len;
+	else
+		goto fail;
+
+	ret = mchp48l640_waitforbit(flash, MCHP48L640_STATUS_WEL, false);
+	if (ret)
+		goto fail;
+
+	kfree(cmd);
+	return 0;
+fail:
+	kfree(cmd);
+	dev_err(&flash->spi->dev, "write fail with: %d", ret);
+	return ret;
+};
+
+static int mchp48l640_write(struct mtd_info *mtd, loff_t to, size_t len,
+			    size_t *retlen, const unsigned char *buf)
+{
+	struct mchp48l640_flash *flash = to_mchp48l640_flash(mtd);
+	int ret;
+	size_t wlen = 0;
+	loff_t woff = to;
+	size_t ws;
+	size_t page_sz = flash->caps->page_size;
+
+	/*
+	 * we set PRO bit (page rollover), but writing length > page size
+	 * does result in total chaos, so write in 32 byte chunks.
+	 */
+	while (wlen < len) {
+		ws = min((len - wlen), page_sz);
+		ret = mchp48l640_write_page(mtd, woff, ws, retlen, &buf[wlen]);
+		if (ret)
+			return ret;
+		wlen += ws;
+		woff += ws;
+	}
+
+	return ret;
+}
+
+static int mchp48l640_read_page(struct mtd_info *mtd, loff_t from, size_t len,
+			   size_t *retlen, unsigned char *buf)
+{
+	struct mchp48l640_flash *flash = to_mchp48l640_flash(mtd);
+	unsigned char *cmd;
+	int ret;
+	int cmdlen;
+
+	cmd = kmalloc((3 + len), GFP_KERNEL | GFP_DMA);
+	if (!cmd)
+		return -ENOMEM;
+
+	ret = mchp48l640_wait_rdy(flash);
+	if (ret)
+		goto fail;
+
+	mutex_lock(&flash->lock);
+	cmdlen = mchp48l640_mkcmd(flash, MCHP48L640_CMD_READ, from, cmd);
+	ret = spi_write_then_read(flash->spi, cmd, cmdlen, buf, len);
+	mutex_unlock(&flash->lock);
+	if (!ret)
+		*retlen += len;
+
+	return ret;
+
+fail:
+	kfree(cmd);
+	dev_err(&flash->spi->dev, "read fail with: %d", ret);
+	return ret;
+}
+
+static int mchp48l640_read(struct mtd_info *mtd, loff_t from, size_t len,
+			   size_t *retlen, unsigned char *buf)
+{
+	struct mchp48l640_flash *flash = to_mchp48l640_flash(mtd);
+	int ret;
+	size_t wlen = 0;
+	loff_t woff = from;
+	size_t ws;
+	size_t page_sz = flash->caps->page_size;
+
+	/*
+	 * we set PRO bit (page rollover), but if read length > page size
+	 * does result in total chaos in result ...
+	 */
+	while (wlen < len) {
+		ws = min((len - wlen), page_sz);
+		ret = mchp48l640_read_page(mtd, woff, ws, retlen, &buf[wlen]);
+		if (ret)
+			return ret;
+		wlen += ws;
+		woff += ws;
+	}
+
+	return ret;
+};
+
+static const struct mchp48_caps mchp48l640_caps = {
+	.size = SZ_8K,
+	.page_size = 32,
+};
+
+static int mchp48l640_probe(struct spi_device *spi)
+{
+	struct mchp48l640_flash *flash;
+	struct flash_platform_data *data;
+	int err;
+	int status;
+
+	flash = devm_kzalloc(&spi->dev, sizeof(*flash), GFP_KERNEL);
+	if (!flash)
+		return -ENOMEM;
+
+	flash->spi = spi;
+	mutex_init(&flash->lock);
+	spi_set_drvdata(spi, flash);
+
+	err = mchp48l640_read_status(flash, &status);
+	if (err)
+		return err;
+
+	err = mchp48l640_set_mode(flash);
+	if (err)
+		return err;
+
+	data = dev_get_platdata(&spi->dev);
+
+	flash->caps = of_device_get_match_data(&spi->dev);
+	if (!flash->caps)
+		flash->caps = &mchp48l640_caps;
+
+	mtd_set_of_node(&flash->mtd, spi->dev.of_node);
+	flash->mtd.dev.parent	= &spi->dev;
+	flash->mtd.type		= MTD_RAM;
+	flash->mtd.flags	= MTD_CAP_RAM;
+	flash->mtd.writesize	= flash->caps->page_size;
+	flash->mtd.size		= flash->caps->size;
+	flash->mtd._read	= mchp48l640_read;
+	flash->mtd._write	= mchp48l640_write;
+
+	err = mtd_device_register(&flash->mtd, data ? data->parts : NULL,
+				  data ? data->nr_parts : 0);
+	if (err)
+		return err;
+
+	return 0;
+}
+
+static int mchp48l640_remove(struct spi_device *spi)
+{
+	struct mchp48l640_flash *flash = spi_get_drvdata(spi);
+
+	return mtd_device_unregister(&flash->mtd);
+}
+
+static const struct of_device_id mchp48l640_of_table[] = {
+	{
+		.compatible = "microchip,48l640",
+		.data = &mchp48l640_caps,
+	},
+	{}
+};
+MODULE_DEVICE_TABLE(of, mchp48l640_of_table);
+
+static struct spi_driver mchp48l640_driver = {
+	.driver = {
+		.name	= "mchp48l640",
+		.of_match_table = of_match_ptr(mchp48l640_of_table),
+	},
+	.probe		= mchp48l640_probe,
+	.remove		= mchp48l640_remove,
+};
+
+module_spi_driver(mchp48l640_driver);
+
+MODULE_DESCRIPTION("MTD SPI driver for Microchip 48l640 EERAM chips");
+MODULE_AUTHOR("Heiko Schocher <hs@denx.de>");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("spi:mchp48l640");